IB-UNICAMP researchers started a study that recently revealed sinister trends on fishing catches. Given that the Paraná River is Brazil’s second largest, these findings are particularly significant. The research, led by Professor Gustavo Quevedo Romero, highlights the detrimental effects of habitat loss and the introduction of exotic species on native fish populations over the past two decades. These results highlight the urgency of addressing these issues to protect our biodiversity while helping local fishing communities.
The Paraná River, the longest river entirely in South America at 5,695 km. int © David Weller The Amazon River, South America’s most important waterway, is a critical resource for local artisanal fishermen. Fishing catches have fallen by nearly half since 2002. This decline parallels catastrophic economic damage in the commercial fishing industry, where revenues have similarly been cut in half. For this, the research focused on data from the Program of Long-Term Ecology of the Upper Paraná River Floodplain (PELD-PIAP), from 2002 to 2022. Social scientists combined satellite-generated land cover maps from MapBiomas with ground-level observations to understand how human occupation of the region was changing.
Impacts of Human Activity on Ecosystems
The study analyzed dammed and undammed environments along the Upper Paraná River floodplain, including five lakes and three river stretches. These conclusions starkly highlight the extent to which human activity has fundamentally transformed local ecosystems. This dramatic change is largely due to the creation of the Itaipu Binacional hydroelectric power plant in 1984. This crucial infrastructural development not only led to the degradation of critical habitats but allowed non-native species to flourish.
Invasive species harm more than just native fish, undermining critical ecosystem services in the process. Brazil’s most populous river basin, the Paraná River basin is home to 32% of Brazil’s population, located within only 10% of its territory. Yet this high density puts even greater environmental pressures, leading to fewer natural spaces, greater competition for resources, and other impacts.
“The replacement of native species by invasive ones is a phenomenon that’s been observed worldwide, with serious impacts on biodiversity and the lives of human populations that depend on fishing. However, few studies have a continuous sample like the one we used, which quite clearly demonstrates the size of the problem,” – Gustavo Quevedo Romero
Local fishermen are incensed by the rapidly dwindling fish stocks. They rely on native species to sustain their livelihoods, and this continuing trend may be putting their livelihoods at risk. Indeed, the market value of capturing a native fish is more than 80 percent greater than that of an invasive fish. As the populations of native fish collapse, fishermen have to catch less and earn less.
Economic Consequences for Local Fishing Communities
Dieison A. Moi, a researcher on the study, highlighted the importance of understanding how these trends impact biodiversity and human communities.
Evidence from research indicates that environmental degradation is increasing. Consequently, flag species such as the spotted sorubim (Pseudoplatystoma corruscans) are becoming increasingly endangered. Fishing guides say they are starting to catch less, and what they do catch are much smaller than their historic predecessors.
“The presence of non-native species erodes the supply of ecosystem services in this region. There’s a cascade effect in which human occupation reduces the coverage of natural areas, harming native species and favoring invasive ones. As a result, native species decrease in size and presence, causing a decline in fishing,” – Dieison A. Moi
The study’s authors highlight the urgent need for long-term ecological research to inform public policies aimed at conserving biodiversity in the Paraná River basin. Under the auspices of FAPESP, the prestigious São Paulo Research foundation, Professor Quevedo Romero heads some very promising projects. These initiatives explicitly aim to improve biodiversity characterization and conservation and restoration activities.
Call for Long-Term Research and Policy Support
The PELD-PIAP program is an invaluable tool for tracking these environmental changes, and understanding how they affect our surroundings over time. Continued investment in such projects is essential to address the cascading effects of habitat loss and invasive species on both aquatic ecosystems and local communities.
“We need resources for long-term studies like the PELD-PIAP, which in turn can provide scientific evidence needed to support public policies in this field and benefit the species and the human population,” – researcher
The PELD-PIAP program plays a crucial role in monitoring environmental changes and assessing their impacts over time. Continued investment in such projects is essential to address the cascading effects of habitat loss and invasive species on both aquatic ecosystems and local communities.